Conventionally, a position detection apparatus has been used in machine tools and the like for detecting the position and amount of movement (amount of change) through rotational movement or linear movement of a moving body. Such a position detection apparatus has been known to be provided with a magnetic sensor capable of detecting change in an external magnetic field accompanying movement of a moving body, and a signal indicating the relative positional relationship between the moving body and the magnetic sensor is output from the magnetic sensor.
A magnetic sensor used in this kind of position detection apparatus has been known to be provided with a magnetic detection element circuit including a plurality of magnetic detection elements, an operational amplifier that amplifies the output signal from the magnetic detection element circuit, and a signal processing circuit for calculating the relative position of the moving body and the magnetic sensor by processing the output signal from the operational amplifier.